An instantaneous coupling device generally comprises a tubular body and means for retaining a pipe in the body in leaktight manner. These means comprise an elastically deformable annular sealing element and a retaining member which are arranged to receive the pipe end. Cam means are interposed between the body and the retaining member to bring the retaining member from a release state in which it releases the pipe end to a grip state in which it grips the pipe end, on the retaining member being displaced axially inside the tubular body from a first position to a second position. Means are provided for resiliently returning the retaining member towards its second position, and by returning the retaining member into said position they tend to hold it in its grip state gripping the pipe end.
Thus, when a pipe end is inserted into the body of the coupling device, it encounters the retaining member in its second position and pushes it back into its first position, thereby putting it into its release state, enabling the pipe end to pass into the retaining member and come into contact with the sealing element. Under the effect of the resilient return means, the retaining member tends to return towards its second position and into its grip state. The resilient return means thus limit the extent to which the pipe end reverses when the fluid transport circuit in which the coupling device is located is put under pressure. The resilient return means also enable a fraction of the operating clearance of the retaining member to be taken up.
The resilient return means are generally constituted by a helical spring mounted between a shoulder in the body and a shoulder on the retaining member. The presence of the spring complicates the design of the coupling device and requires an additional assembly operation.